A recent phenomenon in the marine industry has been the increasing presence of personal watercraft such as the WAVERUNNER and SUPERJET brand watercraft manufactured by YAMAHA WATER VEHICLES, and the JETSKI TANDEM watercraft manufactured by KAWASAKI. These personal watercraft generally comprise small marine vehicles powered by inboard engines. Personal watercraft differ substantially from traditional small watercraft such as row boats, fishing boats and the like. In appearance, most personal watercraft resemble snowmobiles wherein the skis and tracks have been replaced by a hull and propulsion system.
One difficulty facing the designers of such personal watercraft (PWCs) is providing a means for isolating the propeller of the propulsion system from possible entanglement with the body parts of the person using the personal watercraft. The small size, and manner in which PWCs are used often results in riders falling off the PWCs. Additionally, the feet and hands of the user often dangle off of the PWC during use. The use of a traditional, exposed propeller in such situations would likely result in a large number of injuries to users.
To avoid such injuries, the makers of PWCs have generally adopted a propulsion system wherein the moving members of the propulsion system are inaccessible to body parts. Typically, such a system takes the form of a water tunnel formed in the underside of the hull of the PWC. The tunnel typically includes a water intake port comprising a grate disposed generally flush with the underside surface of the hull, an impeller system disposed in the tunnel for drawing water through the water intake port, and a water exhaust port disposed in the rear portion of the hull for propelling water out the rearward end of the PWC to cause it to move forward. The impeller is linked by a mechanical linkage to the engine of the PWC, which typically comprises a motorcycle engine, lawn mower engine or a variant thereof. The above described propulsion system has generally proven quite satisfactory for providing a means for both propelling the watercraft and avoiding injury to users caused by the entanglement of body parts in the system.
Those familiar with boating will appreciate that one of the inconveniences suffered by boaters (including PWC users) involves providing a suitable lift for the watercraft. A suitable lift for watercraft will generally provide three primary features. The first feature is that the lift should provide a secure anchorage for the watercraft, to prevent the watercraft from drifting away from the spot at which it is anchored under the influence of waves, tide and current. A second feature is that the lift should include means that provide ingress and egress to the watercraft. Because of the typical draft requirements possessed by watercraft, many watercraft cannot be placed directly adjacent to the shore. Rather, they must be moored at some distance from shore wherein the water is sufficiently deep to prevent the boat from being "grounded". Typically, some sort of walkway is necessary to enable the user of the boat to travel between the shore and the boat without requiring the user to wade through the water.
A third preferred feature of a lift is that the lift include a platform on which the boat is stored which permits the hull to be raised out of the water, and lowered into the water. When a boat is being stored, it is preferred that the hull be raised completely out of the water to prevent the hull of the boat from becoming fouled by algae, barnacles and the like. In order to use the boat, however, means must be provided to lower the boat into the water to a position wherein the boat can float free of the lift.
Several lifts exist that embody these three features. Probably the most popular type of lift that embodies these three features is a winch-raiseable lift available from several manufacturers. Such a winch-raiseable lift typically includes either four or six generally upright tubular posts that either rest on the bottom of the lake, or are driven into the bed of the lake. These upright posts are connected by a generally rectangular frame that is also made of tubular steel. At least two transverse members extend between the side members of the frame to provide a surface on which the boat can rest. A winch mechanism is provided for raising and lowering the transverse members to raise the watercraft out of, and lower the boat into the water. Typically, the winch mechanism is hand actuated, and comprises a large (e.g. 36" diameter) wheel that is coupled to a winch for drawing cable that extends between the winch and the transverse members.
Although such lifts do perform their intended function in a workmanlike manner, room for improvement exists. One area in which such lifts can be improved is in the convenience of operation of such lifts. The wheel cranking mechanisms are often difficult to use, require a considerable amount of maintenance, and require a considerable amount of effort and time to lift the watercraft completely out of the water.
It is therefore one object of the present invention to provide a lift for a watercraft that permits a watercraft to be raised out of the water for storage, and lowered into the water for launching, which is more convenient than the winch actuated lift described above.